1. Field of the Invention
The present invention generally relates to apparatus for acquiring and storing quantitative information regarding the extent of use of machinery. More particularly, the present invention relates to dump trucks and the like, and to apparatus for acquiring, storing and displaying for the operator real time information concerning the extent of use of the dumping mechanisms thereof.
2. Summary of the Prior Art
In the hauling industry, the number of loads transported by a dump truck during various time intervals is important information. For example, the total number of times the dumping mechanism of a dump truck has been utilized over its lifetime may be important in the calculation of depreciation and/or the determination of the present value of the truck for resale purposes. Similarly, a record of the number of times the dumping mechanism of a dump truck has been utilized since a selected point in time is one way of determining when preventive maintenance on that mechanism is due to be performed. Further, particularly in the case of individual or small dump truck owner/operators, it is not unusual for a contractor to compensate the owner/operator on the basis of an agreed upon amount per load hauled. Accordingly, there is a need in the art for a simple, inexpensive, and automatic apparatus for acquiring, storing and displaying in "real-time" information regarding the number of times the dumping mechanism of a dump truck has been utilized during any one, or all, of numerous predetermined time periods.
Heretofore, dump mechanism utilization information typically has been maintained manually either by the maintenance of hand-written tally sheets, and/or by the operation of manual counting devices. These alternatives are notoriously inaccurate, due both to the possibility of intentional miscounting and to the possibility of inadvertent, unintentional error. Accordingly, information regarding the extent of utilization of the dumping mechanism of a dump truck is often either not available at all, or to the extent that it is available, is totally undependable
In view of this situation, it has been proposed that a microprocessor may be utilized to acquire and store information from various sensors that detect various information concerning a dump truck's operation in the form of histograms. Among these histograms may be one representing the total time during which the dumping mechanism has been in use during a selected time period. The total time recorded by the histogram theoretically is equal to the number of times the dumping mechanism has been used during the selected time period multiplied by a so-called "one shot" time period. This assumes that the so-called "one shot" time period (i.e., that is a predetermined time period corresponding to the "normal" time required for the completion of a dumping cycle) is the average time of the actual dump cycle time periods encountered in the practical use of the mechanism. Of course, this assumption may, or may not, be accurate in any given situation.
Other features are built into this prior apparatus as well in order to ensure the accuracy of the information acquired and stored by the microprocessor. For example, the acquisition and storage of each dumping mechanism duty cycle as part of its associated histogram is conditioned upon the closing of a switch indicating that the dump body has been elevated relative to the frame of the dump truck. Further, this acquisition and storage of information also is conditioned upon the simultaneous closing of a switch that is indicative of the presence of a minimum hydraulic pressure in the hydraulic lifting means for the dump body of the truck. The requirement of the simultaneous closure of these switches ensures that only those operations of the dumping mechanism involving the dumping of a loaded dump body are acquired and recorded by the microprocessor. This is because the pressure in the hydraulic elevation system is not adequate to close the pressure switch unless the weight being lifted thereby substantially exceeds that of the dump body alone. Hence, only elevations of loaded dump bodies can be acquired and stored by the microprocessor.
Still further, in the prior art system briefly described above, a second "one shot" time period cannot be initiated during the course of the recording of the next previous "one shot" time period. This prevents an operator from successively raising the dump body slightly and then lowering it to its rest position numerous times without discharging a load in order to artificially increase the number of dump mechanism cycles registered in the histogram. In addition, the histogram information acquired and stored in the microprocessor is not directly readable therefrom in "real-time", or otherwise. Instead, the histogram information acquired and stored in the microprocessor must be downloaded to a general-purpose digital computer for further processing prior to the system being capable of providing and/or displaying the continuous flow of information represented by the various histograms in a meaningful and usable format. (See, U.S. Pat. No. 4,542,461, issued Sept. 17, 1985 to Eldridge, et al. for APPARATUS FOR ACQUIRING DUMP TRUCK DUTY CYCLE DATA, the disclosure of which is hereby incorporated herein by reference).
Accordingly, a total number of duty cycles of the dump mechanism of a dump truck may be calculated from the prior art histogram based on a "one shot" time period. In addition, the prior art apparatus incorporates desirable features, such as the double sensor configuration, to ensure that only valid information is acquired and stored. However, the information acquired and stored by the microprocessor is not acquired and/or stored in a format that is useful in "real-time" to a user without further external processing. In addition, the prior art apparatus is complex and expensive not only in terms of the capital expense involved in its purchase and installation, but also in its operation. This expense, complexity and lack of readily available output all tend to make the Eldridge, et al. type of apparatus impractical for use by any other than the operators of large fleets of vehicles.
The need in the art for a simple, inexpensive, and automatic apparatus for acquiring, storing and displaying real time information to the operator regarding the number of times the dumping mechanism of a dump truck has been utilized, therefore, remains unfilled.